Controlled deflection roll



Jan. 28, 1964 E. J. Jus-rus 3,119,324

CONTROLLED DEFLECTION ROLL Filed Aug. ze. 1960 2 sheets-sheet aINVENTOR. 04am d, das/a5 MM nu ,L wrrulcx'lfs United States Patent O3,119,324 CONTRLLED DEFLECTION ROLL Edgar J. Justus, Beloit, Wis.,assigner to Beloit Iron Works, Beloit, Wis., a corporation of WisconsinFiled Aug. 29, 1960, Ser. No. 52,456 9 Claims. (Cl. 10G-170) The presentinvention relates to improvements in supported rolls and mechanisms forcontrolling the deflection of the rolls.

In various uses of press rolls and in support or drive rolls deflectionof the roll exists. Mechanisms employ rolls positioned to form apressure nip for rolling materials between them which will cause adeflection of the rolls due to forces at the nip. Other mechanismsemploy rolls subject to deflection forces such as those carrying atravelling belt or web. In paper making machinery, for example, driverolls mounted to engage the loop of the forming wire in a Fourdriniertype paper making machine engage the surface of the wire and the weightof the roll coupled with an applied load arising from the resistance ofthe wire to being driven produce a force component which tends todeflect the drive roll in a direction downwardly and toward the oncomingforming wire. The deflection of the roll tends to cause the off-runningportion of the forming wire to be compacted or squeezed materiallyincreasing the wear on the wire. As well, in press roll couples andother roll arrangements wherein at least a pair of rolls are in nipdefining relationship the algebraic summation of the weight, the nipforces, the bending movements produced by the journal loading, andtorque (if any) tends to produce in each of such rolls a curvature ofits centroidal axis, in accordance with well-known laws of flexure ofmaterials. It is common to attempt to counter this effect by crowningji.e. by grinding the rolls slightly barrel shape in an amount andcurvature calculated to offset the curvature under operating conditions.In certain environments this causes undesirable effects and thedifference in the surface speed of the roll between the central and endportions of the roll is often disadvantageous to the product beingrolled. Various stages in the course of paper manufacturing employ suchroll structures. Efforts have heretofore been made to avoid theundesirable effects of deflection or eliminate the deflection such as byconstructing the rolls with a crowned shape, as referred to above, or byexternally supporting mid-portions of the roll.

A feature of the present invention is to provide a roll and a supporttherefor wherein the deflection of the roll can be controlled toeliminate deflection or to obtain a controlled amount of desirabledeflection.

The mechanism contemplates providing either a single roll, or a pair ofrolls in nip defining relationship. Where a pair of rolls are used, themechanism includes a first roll having support bearings at its ends anda second tubular shaped roll with a plurality of support membersengaging the inner surface opposite the pressure nip between the rolls.A first fluid pressure means is provided for supporting the bearings anda second fluid pressure means is provided for supporting the supportmembers. A selectively controlled pressure source is connected to thepressure means through a ratio control so that a constant ratio ismaintained between the pressure applied to thc 3,119,324 Patented Jan.28, 1964 ICC bearings and to the support members. The support members ina preferred form for a single roll or for the second roll of a pair ofrolls are pivotally carried arcuately shaped shoes which form a film offluid between the shoe surfaces and the inner surface of the second rollfrom fluid carried within the roll.

Accordingly, an object of the present invention is to provide animproved ioll assembly of the above nature in which the deflection of asingle roll is controlled or in which deflection of opposed rolls iscontrolled in an improved manner to obtain a desirable pressure alongthe pressure nip.

A further object of the invention is to provide an improved rollassembly wherein the roll pressures may be selectively changed to obtaindesirable variations in pressure conditions along the pressure nip or toobtain uniform pressure along the nip.

A further object of the invention is `to provide a support for apressure roll which does not have to engage the outer surface of theroll and which supports the inner surface of a tubular roll with `aminimum frictional drag and is capable of a long wearing life.

A still further object of the invention is to provide an improvedpressure roll assembly of simplified construction well suited to use inthe paper industry.

Other objects and advantages of the invention will become more apparentwith the teaching of the principles thereof in connection with thedisclosure of the preferred embodiments in the specification, claims anddrawings, in which:

FIGURE l is a schematic elevational view, with portions in section, ofpressure rolls embodying the principles of the present invention;

FIGURE 2 is a vertical sectional view taken substantially along lineII-II of `FIGURE l; and

FIGURE 3 is a fragmentary sectional view of a portion of the lowerpressure roll illustrating `a modified form of the invention.

As shown on the drawings:

FIGURES 1 and 2 show a first upper roll l0 forming a pressure nip with asecond lower roll 11. The lower roll is tubular in construction. Thefirst roll 10 has a first fluid pressure means or support members 12 atthe ends supporting it and holding it in pressure engagement with thesecond roll 11. A second fluid pressure operated means or supportmembers 13 within the tubular second roll urges the roll upwardlyproviding a support at the inner surface of the tubular roll holding itin pressure engagement with the first roll. A fluid pressure source 14shown in the form of a pump supplies fluid such as air under pressure tooperate the pressure means 12 and 13 and a fluid pressure ratio controlbox 15 is positioned between the pump 14 and the first and secondpressure means 12 and 13 maintaining a predetermined ratio of thepressure of air delivered to the pressure means 12 and 13.

In greater detail, the upper roll 10 has ya supporting shaft 16 carriedon bearings 17 and 18 at the ends of the roll. Fluid pressure members 19and 20 shown in the form of fixedly supported chambers with flexiblediaphragrns apply a downward force to the bearings and the diaphragrnsare connected to the bearings by rods 21 and 22. The various elementsdescribed are illustrated schematically and as will be appreciated bythose skilled in the art may take various other forms. The pressuremembers 19 and 20 for example may take the form of pistons slidablymounted in xed cylinders. The rods 21 and 22 are connected to the endsot lever arms such as illustrated at 23 in FIGURE 2, with the other endof the lever arms mounted on a fixed pivot Z4 and secured at a midpointto the bearings 17 and 18. Accordingly, the downward force applied tothe upper roll will be dependent on the air pressure delivered to thepressure members 19 and 20 and air is delivered through a line 25connected to `the ratio box 15.

As will be understood by those skilled in the art, the ratio box is auid pressure control mechanism or valve assembly which controls theoutlet pressure in output lines maintaining the pressures at apredetermined ratio with the pressures varying as the input pressure butmain taining said ratio. These valves are commercially available andneed not be described in detail.

The pressure to the ratio box may be selectively varied such as by apressure control valve 41 connected to the supply for the ratio box.This may of course be incorporated into the valve of the ratio box.

The second or lower tubular roll 11 is carried on a beam member 26conveniently in the form of a hollow tube. The beam member 26 is mountedat its ends on fixed end supports 27 and 28. The support for thedeliection control pressure applied to the lower roll 11 and for theweight of the roll assembly is provided by the fixed supports 27 and 28.

The lower roll 11 is rotatably positioned by being rotatably mounted onthe beam 26 on bearings 29 and 30 at its ends. The load carried by thebearings 29 and 30 will vary dependent upon the upwardly acting forcesapplied to the inside of the roll 11 by the support members 13 and theprimary support for the roll 11 and the force at the nip N is providedby the support members 13.

The support members 13 are positioned at axially spaced locations withinthe lower roll 11 and engage the inner surface of the lower roll atpositions opposite the pressure nip N between the rolls 10 and 11.

Each support member 13 includes a shoe 31 having an arcuate outer face31a facing the inner surface 11u, FIG- URE 2, of the roll 11. Each shoeis pivotally mounted at 32 on a piston rod 33 supported in a bearingsleeve 37 in the tube shaped beam 26.

The shoes 31 `slide along on the inner surface 11a of the roll 11 anda'supporting film or cushion of lubricant is formed between the outersurface 31a of the shoe and the inner surface 11a of the roll 11 fromlubricant within the roll. Lubricant may be conveniently supplied to theinterior of the roll through a supply tube 38, FIGURE 2. The lubricantmay be a suitable fluid such as oil which maintains the frictional dragbetween the shoes 31 and the roll 11 at a very low amount and alsofunctions to dissipate heat.

These shoes 31 are urged upwardly to provide a backing support for thelower roll 11 by pistons 34, FIGURE l, connected to the lower ends ofthe piston rods 33 and slidably mounted in supported cylinders 35,mounted on supports 39 within the tubular beam 26. Air pressure isdelivered to a lower end of the cylinders 35 through ports 36 connectedto lines 40 to the ratio box 15.

FIGURE 3 illustrates another form somewhat dif ferent in constructionthan the foregoing preferred form, wherein a lower roll 11' is supportedon a plurality of rollers 44 carried on pivotal arms 42 mounted on fixedpivots 43 within the roll 11'. Each of the rollers 44 is forced upwardlyon a piston rod 37' connected to a piston within a cylinder similar tothe construction shown in FIGURES l and 2.

In the aforedescribed arrangements the forces on each of the shoes 31 orrollers 44 are preferably equal inasmuch as this provides the mostpractical and versatile structure. It is contemplated however that theforces applied by different shoes can be diiierent such as, for example,having the shoes at the center of the roll apply a larger force. Thiscould be accomplished by pressure regulators in the lines 4t) anddelivering a higher pressure to certain of the cylinders. lt also couldbe accomplished by providing the pistons 34 and cylinders 35 fordiiierent shoes of different sizes, or it could be accomplished bydecreasing or increasing the spacing between certain support members.

The support members 13 may be employed to achieve various nip loadingei'Iects such as uniform loading across the nip or unequal loading. Theeffect of unequal loading across the nip is useful in paper makingmachinery wherein a paper web passing between the rolls may tend tocrush at the outer edges and may have a less tendency to crush at thecenter of the nip. For this operation a nip load is used wherein agreater load is applied at the center of the rolls than at the edges andthis is accomplished by bowing the lower roll 11 upwardly at the centerto obtain a greater force at the center of the nip.

By way of an example of structure wherein a greater loading at thecenter of the nip can be accomplished, a roll assembly is used whereinthe total area of the diaphragms of the fluid pressure means 19 and 20for the top roll are equal to the total areas of the pistons 34 for thelower roll 1l. A ratio box is used wherein the fluid pressure deliveredto the cylinders 3S is double that of the pressure delivered to thepressure members 19 and 20. A pressure of l0() pounds per square inch inthe line 25 and a pressure of 200 pounds per square inch in the lowerlines 40 will cause the bottom roll to bow up thereby creating a greaterpressure at the center of the nip than at the edges. If the pressures inboth of the lines 25 and 40 are dropped, which can be accomplished byreducing the output pressures of the ratio box such as by reducing thedelivery pressure through the control valve shown schematically at 41,the bowing of the lower roll 11 will decrease thus decreasing thedifference between the pressure at the center of the nip and the edges.At some lesser fluid pressure the pressure along the nip N will becomeuniform. Further reduction in pressure will result in a greater pressureat the edges of the rolls. However. the structure for a particular usewill normally be designed for the nip pressure relationship that is tobe used during normal running operation and the pressure in the nip isalso dependent on factors as the weight of the roll and their strengthor resistance to deection. Thus it will be seen that various effects canbe accomplished both by design and by pressure control.

It is also contemplated that the lower tubular roll `11 be used withoutan upper roll such as for applying a rolling pressure to a surface orfor carrying a travelling belt or wire.

As to the ratio box referred to above, various commercial structures forautomatically providing an output pressure as a function of a variableinput pressure may be employed as will be fully recognized by thoseversed in the art. For example, a device available commercially known asa Kendall biasing regulator could be used with a separate regulator foreach of the cylinders to obtain the fluid pressure desired for eachcylinder with a change in supply pressure.

In paper making machinery, the lower roll may be used to carry atravelling wire as in the Fourdrinier section of the machine. The rollmay also be used as a drive roll for the Wire. The upper roll 10 is ofcourse omitted and a drive mechanism is attached to the lower roll 1l.In carrying a Fourdrinier wire deflection of the roll due to the weightof the wire and due to driving forces on the roll will cause deflectionof the roll to tend to cause the oit-running portion of the forming wireto be compacted or squeezed laterally which substantially increases `thewear on the wire. This deflection of the roll and the ultimateundesirable effects on the wire can be avoided by the roll of theinstant invention wherein the support members 13 are placed at anappropriate location and apply a support force to prevent deflection.

By this it will be seen that l have provided an improved roll assemblywhich meets the objectives and advantages above set forth. The mechanismis susceptible of uses in many fields and provides a reliable structurecapable of long operating life and wherein controlled deflection of theroll is accomplished without undesirable effects and without excessivefrictional drag.

The drawings and specification present a detailed disclosure of thepreferred embodiments of the invention, and it is to be understood thatthe invention is not limited to the specific forms disclosed, but coversall modifications, changes and alternative constructions and methodsfalling within the scope of the principles taught by the invention.

I claim as my invention:

l. In a roll assembly subject to deflection, an elongated tubularcylindrical roll shell adapted to receive lubricating fluid on the innersurface thereof, a rigid support within said roll shell, bearing meansat each end of the roll shell positioning the ends of said roll shellrelative to the support, a shoe inside of said roll shell having anarcuate stationary convex surface supportingly engaging only a portionof the inner circumference of the roll shell, said stationary convexsurface being formed to build up a supporting film of fluid duringrelative rotation of the roll shell from the fluid within the rollshell, and means positioned between the shoe and support for applying apredetermined radial force to said shoe thereby urging said shoeradially outwardly against the inside of the roll shell for controllingdeflection of the roll shell.

2. In a roll assembly subject to deflection, an elongated tubularcylindrical roll shell adapted to receive lubricating fluid on the innersurface thereof, a rigid support within said roll shell, bearing meansat each end of the roll shell positioning the ends of said roll shellrelative to the support, a plurality of shoes axially spaced inside ofsaid roll shell each having an arcuate stationary convex surfacesupportingly engaging only a portion of the inner circumference of theroll shell, said stationary convex surface being formed to build up asupporting film of fluid during relative rotation of the roll shell fromthe fluid within the roll shell, and means positioned between each ofthe shoes and the support for applying predetermined radial forces tosaid shoes thereby urging said shoes radially outwardly against theinside of the roll shell for controlling deflection of the roll shell.

3. In a roll assembly subject to deflection, an elongated tubularcylindrical roll shell adapted to receive lubricating fluid on the innersurface thereof, a rigid support within said roll shell, bearing meansat each end of the roll shell positioning the ends of said roll shellrelative to the support, a plurality of shoes axially spaced inside ofsaid roll shell each having an arcuate stationary convex surfacesupportingly engaging only a portion of the inner circumference of theroll shell, said stationary convex surface being formed to build up asupporting film of fluid during relative rotation of the roll shell fromt'ne fluid within the roll shell, means pivotally supporting each ofsaid shoes about an axis parallel to the roll shell axis, and meanspositioned between each of said pivotal supporting means for the shoesand said support for applying predetermined radial forces to said shoesthereby urging said shoes radially outwardly against the inside of theroll shell for controlling deflection of the roll shell.

4. In a roll assembly subject to deflection, an elongated tubularcylindrical roll shell adapted to receive lubricating fluid on the innersurface thereof, a rigid support within said roll shell, bearing meansat each end of the roll shell positioning the ends of said roll shellrelative to the support, a shoe inside of said roll shell having anarcuate stationary convex surface supportingly engaging only a portionof the inner circumference of the roll shell, said stationary convexsurface being formed to build up a supporting fllm of fluid duringrelative rotation of the roll shell from the fluid within the rollshell, and a fluid motor positioned between the shoe and support forapplying a predetermined radial force to said shoe thereby urging saidshoe radially outwardly against the inside of the roll shell forcontrolling the deflection of the roll shell.

5. In a roll assembly subject to deflection, an elongated tubularcylindrical roll shell adapted to receive lubricating fluid on the innersurface thereof, a rigid support Within said roll shell, bearing meansat each end of the roll shell positioning the ends of said roll shellrelative to the support, a plurality of shoes axially spaced inside ofsaid roll shell each having an arcuate stationary convex surfacesupportingly engaging only a portion of the inner circumference of theroll shell, said stationary convex surface being formed to build up asupporting film of fluid during relative rotation of the roll shell fromthe fluid within the roll shell, a force applying means positionedbetween each of the shoes and the support, and means for individuallyoperating each of the force applying means so that independent forcesmay be applied to each of the shoes urging the shoes radially outwardlyagainst the inside of the roll shell for controlling deflection of theroll shell.

6. A pressure rolling mechanism comprising a first rotatable roll, asecond rotatable roll shell, a first variable pressure means providing asupport for the first roll holding it in pressure engagement with saidsecond roll shell forming a pressure nip therebetween, a plurality ofsupport elements in engagement with the inner surface of said secondroll shell opposite the pressure nip, second pressure means havingindividual members connected to said support elements providing asupport for the second roll shell and controlling deflection thereof forobtaining a predetermined nip load, said members being individuallycontrollable for applying pressures to obtain a predetermined nip loadcharacteristic along the nip, nip loading means connected to said firstand said second pressure means for changing the nip load, and ratiocontrol means connected to said nip loading means and to said fluidpressure members controlling said individual memhers to retain saidpredetermined characteristic with change in nip load.

7. A pressure rolling mechanism in accordance with claim 6 wherein saidratio control means provides a uniform nip pressure along the length ofthe nip at different operating nip loads.

8. A pressure rolling mechanism comprising a rst rotatable roll, atubular second rotatable roll shell, a first Variable fluid pressuremeans providing a support for the first roll holding it in pressureengagement with said second roll shell forming a pressure niptherebetween, a plurality of support elements in engagement with theinner surface of the second roll shell opposite the pressure nip, secondvariable fluid pressure means having individual members connected tosaid support elements providing a support for the second roll shell andcontrolling deflection thereof, said members being individuallycontrollable for applying pressures to obtain a predetermined nip loadcharacteristic along the nip, a fluid pressure supply means connected tosaid first and second pressure means for changing the pressure of thesupply fluid and changing the nip load, and ratio control meansconnected to said fluid pressure members controlling said individualmembers to retain said predetermined characteristic with change in nipload.

9. A pressure rolling mechanism comprising a first rotatable roll, atubular second rotatable roll shell, a support for the first rollholding it in pressure engagement with said second roll forming apressure nip therebetween, a plurality of support elements in engagementwith the inner surface of the second roll shell opposite the pressurenip, variable fluid pressure means having individual members connectedto said support elements providing a support for the second roll shelland controlling deflection thereof and nip pressure, said members beingindividu ally controllable for applying pressures to obtain n uniformnip load characteristic along the nip, nip loading means connected tosaid variable pressure means forchanging the total nip load, and ratiocontrol means connected to said nip loading means and said uid pressuremembers controlling said individual members to retain said uniformcharacteristic along the nip with change of said nip loading means.

References Cited in the file of this patent UNITED STATES PATENTSSchurmnnn May 24, Stacom Jan. 21, Specht Mar. 15, Hornbostel Aug. 11,Appcnzelier Oct. 20, Keyser Aug. 30, Kuster Mar. 6,

1. IN A ROLL ASSEMBLY SUBJECT TO DEFLECTION, AN ELONGATED TUBULARCYLINDRICAL ROLL SHELL ADAPTED TO RECEIVE LUBRICATING FLUID ON THE INNERSURFACE THEREOF, A RIGID SUPPORT WITHIN SAID ROLL SHELL, BEARING MEANSAT EACH END OF THE ROLL SHELL POSITIONING THE ENDS OF SAID ROLL SHELLRELATIVE TO THE SUPPORT, A SHOE INSIDE OF SAID ROLL SHELL HAVING ANARCUATE STATIONARY CONVEX SURFACE SUPPORTINGLY ENGAGING ONLY A PORTIONOF THE INNER CIRCUMFERENCE OF THE ROLL SHELL, SAID STATIONARY CONVEXSURFACE BEING FORMED TO BUILD UP A SUPPORTING FILM OF FLUID DURINGRELATIVE ROTATION OF THE ROLL SHELL FROM THE FLUID WITHIN THE ROLLSHELL, AND MEANS POSITIONED BETWEEN THE SHOE AND SUPPORT FOR APPLYING APREDETERMINED RADIAL FORCE TO SAID SHOE THEREBY URGING SAID SHOERADIALLY OUTWARDLY AGAINST THE INSIDE OF THE ROLL SHELL FOR CONTROLLINGDEFLECTION OF THE ROLL SHELL.